2013 Annual Report
1a.Objectives (from AD-416):
The overall objectives of this continuing long-term project are to develop improved perennial grasses, management practices, and technologies for use in grazing lands and biomass energy production systems in the central USA. Over the next five years, the following specific objectives will be addressed. (1) Develop best management practices for Midwest and central Great Plains perennial grass, mixed grass, and grass-legume pastures to increase livestock production, provide biomass feedstocks for bioenergy production, and maintain ecosystem services; (2) Develop new cool- and warm-season grass cultivars and native legume germplasm for Midwest and Great Plains growing conditions; and (3) Identify biomass characteristics that impact conversion efficiency to liquid fuels. Utilize this information to develop improved breeding criteria and improved management practices.
1b.Approach (from AD-416):
Improved perennial grasses and legumes and associated management practices will be developed for use in the Central Great Plains and Midwest for bioenergy production and grazing when grown on land that is unsuitable or marginal for grain crop production. Perennial plant breeding technologies will be used to develop the improved cultivars. Improved management methods will be developed to fully utilize the genetic potential of the new cultivars by enhancing establishment, yields, and utilization by livestock, and all aspects of biomass energy crop production. Basic molecular biology and biochemistry/physiology information will be developed that will improve the breeding and management products. The project is a continuation of a long-term perennial grass project that has plant materials, management, and basic science studies in various stages of development and completion. Research will be conducted on both C3 (cool-season) and C4 (warm-season) grasses because both are needed in the region to maximize the length of the grazing season. Switchgrass, big bluestem, and indiangrass will be the primary C4 species and will be developed for use in both bioenergy and livestock production systems. Smooth and meadow bromegrass and intermediate, tall, and western wheatgrass will be bred for use in cool-season pastures. Native legumes will be enhanced for use with C4 grasses in biomass production systems. Grass technologies from this research when utilized on 6 million hectares in the Midwest could produce biofuels for 15 million cars. Beef production per hectare from pastures with new cultivars and improved management could be improved by 10 to over 25%.
New seed lot quality tests for big bluestem and indiangrass have been initiated by collecting seed lots for evaluation. External chemical treatments that could improve seed germination in newly harvested and dormant seeds of switchgrass were tested. It was found that after-ripening was a key requirement in switchgrass seeds that cannot be efficiently replaced by chemical treatments. Year 3 of the bromegrass grazing trial was completed. Seed increase of the experimental bromegrass strain in the grazing trial is in process for potential release of a new cultivar. The second year of the warm-season grazing trial was initiated and is in process. The project-developed cultivars of big bluestem, indiangrass, and switchgrass produced excellent beef cattle gains during the severe drought in 2012 in both pure stands and mixtures. Year 16 of the long-term switchgrass and no-till corn bioenergy study was initiated. A study on the C and N flux and soil quality based on the plots in this study has been completed. A comprehensive analyses of the net energy and greenhouse gas status for the first 10 years of this combined no-till corn and switchgrass experiment with different N fertilizer and harvest management treatments has been completed. Multi-location field trials have been established in NE, IA, IL, IN, MN, and WI to evaluate management practices for biomass production.
Molecular aspects of perennial grass autumn senescence and seasonal dormancy are linked to winter survival. Research has been continued on these processes in switchgrass. RNA extracted from crowns and rhizomes of field grown plants harvested at different times during the growing season were subjected to high-throughput sequencing. These large datasets are being extensively analyzed and have been deposited into publically-available databases. These and other available data were mined to understand the expression of a specific family of enzymes (class III peroxidases) which can play significant roles in plant stress responses and have been summarized.
Plant cell wall properties can positively or negatively impact conversion of biomass into liquid fuels. Identification of genetically related plants with the most divergent cell wall properties can be utilized to both understand physical factors that affect cell wall deconstruction as well as potential changes in traits and gene-expression that control cell wall formation. To this end, plants from several breeding nurseries have been identified that differ significantly in biomass composition and are being studied.
New polycross nurseries were established for six switchgrass, two sand bluestem, and four bromegrass populations to produce advanced generation experimental strains. An improved greenhouse crossing method was developed and used to produce full-sib switchgrass families using paired plant crosses in the greenhouse. Greenhouse grown progeny of these crosses was used to establish field evaluation nurseries of the F1 hybrid families. Additional selection nurseries were established for switchgrass and a native legume. Biomass harvests of breeding nurseries in the 2nd or 3rd evaluation year were completed as scheduled.
Improved smooth bromegrass strain increases beef cattle gains on pastures. Improved cool-season grasses are needed in the Midwest and Northern Great Plains to improve beef cattle gains per acre and profitability. An experimental smooth bromegrass strain developed from the cultivar ‘Lincoln’ by four generations of recurrent breeding for increased forage yield and digestibility by an ARS geneticist at Lincoln, NE was evaluated in a replicated grazing trial with beef yearlings for three years by ARS and University of Nebraska scientists. Cattle grazing the experimental bromegrass strain had 3-year average daily gains of 3.1 lbs per head per day during spring grazing. The 3-year average body weight gain of 349 lbs per acre during the spring grazing season was 12% greater than that for the widely used smooth bromegrass parent cultivar Lincoln demonstrating that the genetic improvements in smooth bromegrass can have significant economic value when used in well managed pastures. The smooth bromegrass experimental strain is in seed increase for potential release as a new cultivar. It can be used to meet the demand for improved cool-season pastures in the Midwest and Northern Plains.
Identified a total of 342 class III peroxidases genes in the switchgrass genome. Work with other grasses have shown that increases in the levels of specific class III peroxidases are associated with improved resistance to herbivory by piercing-sucking insects. Such information is unavailable for switchgrass. In this work performed by ARS researchers at Lincoln, NE, in collaboration with University of Nebraska scientists, the presence or absence of all the class III peroxidases was documented in switchgrass tissues at different stages of plant development. Using this data, it is now possible to identify specific switchgrass peroxidase genes that are involved in the plant’s response to insect herbivory. Data obtained by these new analytical methods can be used by plant breeders and other researchers to develop switchgrass strains with improved resistance to piercing-sucking insects.
Improved bioenergy type switchgrass cultivar with high biomass yield tested and increased for use in the northern half of the USA. Switchgrass cultivars for the northern half of the US have been limited to upland ecotype switchgrass cultivars because available lowland cultivars have poor winter survival in the region. Lowland switchgrass cultivars have the potential to produce greater biomass yields if they had better winter survival. A new lowland type switchgrass cultivar ‘Liberty’ will be released in 2013. Liberty which was developed by ARS researchers at Lincoln, NE by crossing northern upland and southern lowland plants followed by three generations of breeding for winter survival, high biomass yield, and low stem lignin concentration. Over a three year period in trials in NE, WI, and IL, Liberty had excellent winter survival and in eastern Nebraska and northern Illinois had biomass yields that were 2 tons per acre greater than the best available released upland cultivars. The experimental strain is in the ARS cultivar release process and has been planted in a Foundation seed increase field. It will be the first bioenergy type cultivar for the Midwest and the northern Great Plains and will likely also be used in the Northeast states. When processed in a biorefinery, the increased biomass yield will result in an additional 160 gallons of ethanol per acre which could fuel an economy car for 5000 miles.
Watrud, L., Reichman, J., Bollman, M., Smith, B., Lee, E., Jastrow, J., Casler, M.D., Collins, H.P., Fransen, S., Mitchell, R., Owens, V.N., Bean, B., Rooney, W.L., Tyler, D.D., King, G.A. 2012. Chemistry and microbial functional diversity differences in biofuel crop and grassland soils in multiple geographies. BioEnergy Research. 6(2):601-619.
Mitchell, R., Vogel, K.P., Sarath, G. 2012. Predicting the field establishment of perennial grass feedstocks: progress made and challenges ahead. Biofuels. 3:653-656.
Uden, D.R., Mitchell, R., Allen, C.R., Mccoy, T., Guan, Q. 2013. The feasibility of producing adequate feedstock for year–round cellulosic ethanol production in an intensive agricultural fuelshed. BioEnergy Research. doi 10.1007/s12155-013-9311-x.
Bowman, M.J., Dien, B.S., O'Bryan, P.J., Sarath, G., Cotta, M.A. 2012. Comparative analysis of end point enzymatic digests of arabino-xylan isolated from switchgrass (Panicum virgatum L) of varying maturities using LC-MS(n). Metabolites. 2(4):959-982.
Saathoff, A.J., Donze, T., Palmer, N.A., Bradshaw, J., Heng-Moss, T., Twigg, P., Tobias, C., Lagrimini, M., Sarath, G. 2013. Towards uncovering the roles of switchgrass peroxidases in plant processes. Frontiers in Plant Biotechnology. 4:1-12. doi 10.3389/fpls.2013.00202.
Kovacs, F., Sarath, G., Woodworth, K., Twigg, P., Tobias, C.M. 2013. Abolishing activity against ascorbate in a cytosolic ascorbate peroxidase from switchgrass. Phytochemistry. doi 10.1016/j.phytochem.2013.05.016.